The present invention relates to earthquake actuated shutoff valves and in particular to earthquake actuated gas shutoff valves including a ball and seat.
There is world wide concern regarding the effects of earthquakes. In recent years, earthquakes occurring around the world resulted in tens of thousands of deaths. Although modern building codes drastically reduce the human harm resulting from earthquakes, there is still a significant likelihood that deaths will occur even in modern countries. Although building codes have been successful in reducing the catastrophic collapse of structures, there is often substantial secondary damage resulting from gas fires, broken electrical wiring, and the like. Various devices have been developed to turn off gas lines and the like, either directly through a mechanical action, or indirectly through actuation of an electrical switch.
U.S. Pat. No. 4,185,507 for “Acceleration Responsive Tripping Mechanism,” describes a ball sitting on a pedestal. When motion occurs, the ball falls off the pedestal into a surrounding chamber (or dish), causing the chamber to lower against a spring, and to trip a micro switch. Disadvantageously, the device of the '507 patent includes a number of moving parts including a spring, vertically moving piston, and levers. Devices such as this are generally mounted, and forgotten. There is typically little to no inspection or maintenance, and as a result, such complexity is an invitation to failure.
U.S. Pat. No. 4,261,379 for “Vibration/Temperature Sensitive Valve Operating Apparatus,” describes a ball siting in a cup. Motion causes the ball to fall out of the cup, and the cup raises slightly, this motion releases a trigger which results in the desired actuation. Unfortunately the '379 patent also includes substantial mechanical complexity, including several arms, springs, and pins. Such mechanical complexity is undesirable for the reasons cited above.
A simpler valve is disclosed in U.S. Pat. No. RE38,220 for “Earthquake Actuated Automatic Gas Shutoff Valve” filed by the present applicant. The '220 patent describes a simple but effective valve using a solid elastomeric ball or a ball coated with an elastomeric outer coating. While the valve of the '220 patent provides many advantages over previous valves, there are instances where the valve is connected to gas lines which are not sufficiently vertically aligned to provide proper ball and seat interaction. The '220 patent is herein incorporated by reference.